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Compact rental apartment construction requires special refurbishment concepts for efficient heating systems.
© Michael Gaida, pixabay.com (Symbolbild)
Building refurbishment

Exemplary low-exergy energy supply concept for an existing multi-family home consisting of an electric heat pump, a storage tank for drinking water / heating water, a decentralised fresh water station as a 4-pipe system and auxiliary electric heating for domestic water heating either centralised or decentralised.
© Fraunhofer ISE

Optimising heat pumps for multi-family homes

Solutions for the application of low-exergy systems are being developed to supply heat to existing multi-family homes. This building services equipment includes electric and gas heat pumps as well as heat transfer and ventilation systems. Different system concepts are assigned to different building types and refurbishment processes and then evaluated. The aim is to realise and evaluate the developed heat pump systems and components in exemplary refurbishment projects.

Around half of the apartments in Germany are in multi-family homes (MFH). Most of the large MFHs were built in the 1970s, while most of the smaller MFHs date back to the 1960s. The buildings generally do not have any ventilation systems. The heating systems are used for space heating as well as domestic hot water heating and are mainly operated with gas.

To ensure a successful energy transition, sustainable technologies must be used to supply heat to these existing buildings. Heat pumps driven by electricity or thermal energy have considerable potential to reduce the specific C02 emissions for heat supply in refurbished buildings. However, this places special requirements both on transfer systems for space heating and domestic hot water provision (heat sinks) and on the utilisation of environmental heat (heat source). This is especially true if the exergy requirement for heat provision is to be kept low.

Low-exergy systems for multi-family homes

In a joint project, solutions for the use of electric and gas heat pumps, heat transfer and ventilation systems in energetically refurbished buildings are to be analysed, developed and demonstrated and evaluated in multi-family homes. User comfort, economic aspects and the reduction of emissions are decisive criteria. The aim is to further develop the systems for the refurbishment of existing buildings, to increase their economic efficiency and to ensure safe and energy-efficient operation.

The Solar Construction / Energy-Efficient City support initiative

The project is being funded as part of the Solar Construction/Energy-Efficient City support initiative set up by the German Federal Ministry for Economic Affairs and Energy and the German Federal Ministry of Education and Research. Module 1, called “Solar Construction”, focuses on projects concerned with energy-efficient buildings and building ensembles. The project presented focuses on the analysis of existing multi-family homes with a view to low-exergy systems and the development of corresponding system concepts for the refurbishment of multi-family homes.

A detailed description of this research partnership can be found on the portal for the ENERGIEWENDEBAUEN research initiative.



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Coordinaton, project management
Albert-Ludwigs-Universität Freiburg, INATECH

Project partner

Project partner
Fraunhofer ISE

Energy-efficient modernisation with low-exergy systems
Project business card on the ENERGIEWENDEBAUEN website

Projects, reports, news and analysis from the research initiative ENERGIEWENDEBAUEN

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